Electric-furnace process and electric furnace.



o. HERING. A ELECTRIC FURNACE PROCESS AND ELECTRIC FURNACE.

APPLICATION F-ILED JULx e,19o9.

- Patented Apr. 4, 1911.

2 SHEETS-SHEET 1.

I Q/Vitnmm O, HEBING. ELECTRIC FURNACE PROCESS AND ELECTRIC FURNACE.

' Patented Apr. 4, 1911.

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UNITED snares PATENT OFFICE.

CARL HERING, 0F PHILADELPHIA, PENNSYLVANIA.

ELECTRIC-FURNACE PROCESS AND ELECTRIC FURNACE.

Application filed July 6, 1909. Serial No. 505,963.

My invention resides in an-electric fur nace wherein the resistercomprises a column or columns of molten material, electrodes furnishingcommunication with said columns, the heat in the column resister beingcommunicated to the main body or mass of molten or other material undertreatment by conduction from such resister and chiefly by convection andrapid circulation; and it is a further feature of my invention that I soconstruct and proportion the column resister that the pinch effect insuch column is usefully availed of for causing more or less violentcirculation and movement of the heated material from the columns intothe mass of molten material under treatment.

My invention resides also in other forms of electric furnace in whichthe pinch effect above referred to, is usefully availed of for causingstirring or agitation of material under treatment.

My invention resides also in other modified forms of this type offurnace hereinafter described. 1

My invention resides also in the use with such furnaces of furnaceelectrodes, which, if made in accordance with myinvent-ion, are farsmaller and cheaper as compared with former general practice and whichgreatly reduce the electrode losses, whereby the efliciency of thefurnace is considerably increased.

My invent-ion resides also in the improved processes of electricallytreating .materials as hereinafter described.

My invention resides in other features hereinafter pointed out andclaimed. i

Specification of Letters Patent.

Patented Apr. 4., 1911.

For an illustration of some of the forms my invention may take,reference is to be had to the accompanying drawings, in which:

Figure 1 is a vertical sectional view of an electric furnace in whichthe resister is in the form of a column or columns of molten materialcontacting with the electrodes and communicating with the main mass ofmolten material above it. Fig. 1 is a cross sectional view of a modifiedform of conductor column or channel. Fig. 2 is a vertical sectional viewof a similar furnace in which, however, the resister column is inclined,whereby there will be less hydrostatic pressure in the resister column.Fig. 3 is a horizontal sectional view of a furnace similar to the typeshown in Fig. 1 and adapted for the use of three phase alternatingcurrents. Fig. 4 is a vertical sectional view of a plural furnace, suchas may be used, for example, in the production of steel directly fromiron ore. Fig. 5 is a vertical sectional view of an arc furnace, the arebeing struck between two baths of fused metal, the furnace involvingalso other features herein described. Fig. 6 is a side elevational viewof a metallic or conducting starter. 'Figs. 7 and 8 are Verticalsectional views of combined arc and resister furnaces wherein aplurality of arcs are employed in series. Fig. 9 is a vertical sectionalView of an arc furnace in which the arc is started by the pinch elfect.

Referring to Fig. 1, an electric furnace is shown in vertical sectionand having abroad fiat hearth A, which is especially suitable for thetreatment of iron, or other materials when a large exposed surface isrequired; the hearth may take any suitable or desired form, as the heatproducing resister is practically independent of the proportions of thishearth or of the amount of material in it. Upon the hearth A is a mass Bof molten iron or other conducting material under treatment, the moltenmaterial extending also downwardly into the columns C and D, the moltenmaterial in these columns making electrical contact with the furnaceelectrodes E, E which extend through the bottom or jacket.

wall of the furnace, and may terminate outside in conductingenlargements F, F which i material by a casting preferably of the samematerial as that to be treated, extending downwardly in the columns Cand D into contact with the electrodes E, E, such casting beingcontinuous and bridging the columns O and D at the top. When the currentis turned on, it flows from one electrode through one of the columns andout through the other column and other electrode, the casting becominghotter and hotter until finally melted. Then the usual mixture of ore,carbon and flux is introduced, it being preferably in suflicientquantity above the hearth to force anasses of it into the molten mass,whereupon the heat of the molten mass B is rapidly conveyed to it,thereby hastening the chemical action such as the combination of ironand carbon on'the one hand, and the combination of the carbid, thusformed, with the iron oxid, on the other hand, as is well understood inthe art. J represents the slag. And a further opening L may be providedfor the introduction of.

air, as by a blast, for burning any possible unburned gases which may beformed, like carbon monoxid, thus preheating the ore and therebyincreasing the economy of heat of the furnace. In fact, the part of thefurnace above the mass B may be an ordinary blast furnace where thenecessary heat is procured by ordinary combustion. duced metal thencollectsas the mass B in the hearth A where it is further heatedelectrically and where, by the introduction of more ore, it can bedirectly oxidized into steel. By this arrangement, cooling and reheatingin a separate chamber or furnace is avoided with resultant. increasedeconomy. M is a tap hole communicating with the column C for drawin offthe reduced iron or other material, anda similar tap hole N may beprovided for communicating with the other column D for the same purpose,if desired. Or the tap'hole may communicate with the bottom of thehearth A, if desired, or tap holes may be placed at both places. Inoperation, the heat is produced by the current in the columns G and D,the molten masses in these columns constituting the resister. This heatis then conducted to the mass B through the columns C and D, and thedelivery of the heat'to the mass B is further procured, and chiefly, ifdesired, by the pinch effect caused in the columns G and The re- D bythe currentfiowing through them, this pinch effect causing the moltenmetal to flow up through the central axis of the columns and thehydrostatic pressure will then cause it at thesame time to flowdownwardly at the circumference of the columns. This pinch effect may bemade so great, if desired, as to causean actual squirting of the moltenmaterial up through-the mass B into contact with the lower layers of theore and slag. This pinch effect may be secured by properly proportioningthe cross section of the col umns C and D with respect to the currenttraversing them. The pressure developed by the current'flowing in such acolumn of liquid conductor may be expressed by the following. formula:

where p represents the pressure in pounds per square inch at the centralaxis, 0 is a constant, C the current in amperes and S the cross sectionof the liquid column in square inches. It is apparent, therfore, that tosecure a strong pinch effect the ratio of the square of the current tothe cross section of the column should be large. The greater this ratiothe greater will be the pinch effect, and, as above stated, this effectmay be made so great as to actually squirt the molten material upwardlythrough the mass B in the hearth A into contact with the lower layers ofthe ore or other material to be reduced or otherwise treated, wherebyeffective stirring or agitation is procured, and the heat generated inthe resisters 'is rapidly conveyed to the mass above them.

A side column 0 communicating with the mass B and with a column, as l),at a distance below the mass B may be provided for further stimulatingthe circulation of the molten mass. The section of the column 0 may beso chosen that, with the current passing through it, a differentpressure is produced by the current within it from that produced in thecolumn, as D, with which it communicates, so that this difierence inpres? sure in the two columns will cause a circulation. However, suchside column Omay be omitted and the pinch effects in the main columnsthemselves may be availed of for securing the circulation and rapidtransfer of heat to the mass above.

The columns C and D are preferably made slightly conical with thegreatest diameter at the end nearest the bath B in order that when themetal solidifies in the bath and columns the columns will not break dueto the contraction of the solidifying metal. And as shown at y one ormore of the columns may be contracted just below the molten mass B inorder to have a greater pinch effeet in the region of the contraction.

As shown in Fig. l in cross section, the

. ing at high temperatures may be used for the tube, rod, or plate. Andin the furnace wall or in the furnace material lying between the.

columns C and D may be provided an air space it to insure that currentwill not pass directly from one column to another through the furnacewall material in case such material should be conduct-ing at hightemperatures:

In Fig. 2 the arrangement and construction are substantially the same asshown in Fig. 1, except that the columns are inclined, in place ofVertical, so that less hydro-static pressure is developed in thecolumns. By this means, the pinch effect developed is required toovercome a smaller hydro-static pressure of the molten material, and theangle through which the furnace must be tilted in order to completelyempty it, becomes much less.

Since by this construction of the furnace, the current flows through aresister column and then through the mass of molten material in thehearth, alternating current of three phases, or other number of phases,may be readily employed. As shown in Fig. 3, in

. horizontal section, there communicate with the hearth A three columnsC, D, and P, one for each of the three currents, the connection beingthen a Y connection, the mass of molten metal in they hearth A formingthe common junction for the three legs or columns of the three phasecircuit. I

v In Fig. 4 I have shown in vertical section a plural furnace, the lefthand unit being substantially the same as shown in Fig. -1. In this lefthand unit the ore may be reduced'or otherwise treated to form a moltenmass B, as heretofore described. From time to time the taphole Q may beopened, access to such tap hole being provided by the opening R in theopposite side of the second unit. In this second unit the refining isdone by treatment by the usual slags, oxids, or other materials whichmay be introduced through.

the top opening I', the molten mass B be ing drawn from the mass B inthe first unit. Here again the liquid columns C and D, communicatingwith the electrodes E, E, are provided with tap holes M and N fordrawing off the refined material.

By a furnace of this construction steel may be made directly from ironore. The reduction or treatment of the ore occurs in the left-hand unitand the refining inthe right hand unit. By this process, steel may bemade from the ore Without cooling and reheating the unrefined iron. Theore is reduced by electrically produced heat in part or wholly, and witha minimum loss of heat,

because the electrical resistance is always practically entirely in thecolumns, as C, D,

and is not materiall changedby increasing the surface or depth of themass B in the hearth A. And the stirring action due to the pinch effectmay be made as great as one desires even to the extent of a violentsquirting of the material through the slag and material above it, thusexposing a very large surface to the slag and other materials. I may,therefore, use the furnace as shown in Fig. 1 for the direct productionof steel from the ore by feeding the mixture of ore, carbon and flux inat I, which will cause the solids to be forced into the bath B of moltenmaterial, thereby coming into direct and intimate contact with it. Theheated gases will give off their heat to the descending raw material,thereby also utilizbe drawn oil into a second furnace as shown in Fig. 4where it is oxidized into steel and refined. In either case this may bedone by the well known methods of adding-oxid of iron, or ore, to thepig iron to reduce the carbon, and the various slags may be addedtoreduce the sulfur, phosphorus, etc. All. this becomes very simple andrapid in a furnace in which the heat is generated in the material ofgood conductivity and trans ferred from it by rapid agitation to theother ingredients. And as described in connection with Fig. 1, the firstunit of the plural furnace shown in Fig. 4 may be replaced by anordinary blast furnace wherein the necessary heat is secured bycombustion, the molten material then being drawn off to the second unit,as above described, for further treatment.

It is possible, of course, to use this type of mass to be heated, likeore, slag, glass, or mixtures of materials, as for instance, in thereduction of zinc, production of arsenic either metal or oxid from itsores, also the production of calcium carbid, ferro alloys, etc, wheneverthe temperature re-' qulred is less than the volatilization temperatureof the liquid resister. The specific gravity of the resister should thenbe greater than thatof the material to be treated and the two materialsshould be miscible. v

I have found that the energy loss in the furnace electrodes may bereduced greatly below what has heretofore been commonpractice. electrodelosses and from it I have found that for a minimum amount of loss in theelectrodes, such electrodes must be so proportioned that the (FR loss(heat generated by current in the resistance of, the electrodes) shall.be equal substantially or approximately to twice the heat conductionloss of the electrodes. By heat conduction loss I mean the loss of heatfrom the interior of the furnace through the electrodes by heatconduction, when no current is flow ing. I have found that for any otherrelation between these two losses the combined loss becomes greater. Asaresult of proportioning the electrodes so that this relation shall hold,the losses of energy in and through the electrodes become very small ascompared with prior practice. The total loss in the electrodes will thenbe equal to the electrical resistance loss only, (C R loss),

as there will then be no heat lost by conduction, because thetemperature of the hot end of the electrode will then be equal to thatof the furnace, and the electrode will therefore bethe equivalent of aperfect heat insulator, allowing no heat to pass through it from thefurnace, although the electrode remains a very good electricalconductor. No material is known which has these two qualities combined,namely, heat insulation and electrical conductivity but by proportioningthe electrodes according to the laws which I have discovered, thepractical equivalent of these two properties can nevertheless berealized. From these laws I find that the minimum loss is generallyleast for the metals, and that it is very considerably less than for theusual materials carbon and graphite. It is a part of my invention,therefore, that metal electrodes are employed, preferably of the samemetal as is melted in the furnace, or of metal or material which doesnot contaminate the material or metal fused inv the furnace, and therebyI can greatly reduce the electrode losses. ,To obtain this advantage ofa lower minimum loss for metal electrodes they must be proportioned sothat the heat conduction loss, with no current flowpreferably not I havediscovered the law of the ing, will be equal to half the 0 R lossapproximatelyor substantially. But my improvement is not-limited tometal electrodes, for, by observing the novel proportions hereindescribed, carbon and graphite electrodes, giving minimum losses forthose materials, may be employed, and the loss will be found to be muchsmaller than for the carbon and graphite electrodes as heretofore used.From the laws which I have discovered it follows that this economy ofmaterial will be greatest, that is, for any given length the crosssection will be least, when the square root of the product of theelectrical and the thermal conductivities is greatest. Hence, I findthat as far as economy of material is concerned, those materials arebest in which this product is greatest. From the conductivities ofdifferent materials as far as they are known, I find, from thelaw whichI have discovered, that the square root of these quotients and productsare as a rule greatest for the metalsas distinguished from the usualelectrode materials,carbon and graphite. The difference isgreat. Hence,I have found it much more economical to use metal electrodes wheneverpossible.

When metal electrodes are used and proportioned in accordance with thelaws which I have discovered, they will remain solid at the externalends although they will be at the temperature of fusion at the inside orfurnace ends. The reason is that, when so proportioned there will be noheat conducted by the electrodes from the interior of the furnace, andall \the heat generated in them by the current will be led offv at thecool or outside end just as fast as it is generated in it; hence theirtemperature will not in crease and they will remain unfused except attheir extreme inside ends. If continuously covered with fused metal attheir inside or hot ends they will not be consumed and if made of thesame metal as that fused in thefurnace, or of one which is non-misciblewith the fused material, they will not contaminate the latter. Thisstate, as I have found, is also the state of least total loss in theelectrodes.

From the laws above stated I have de- -duced the following formula:

X 2.894 CV75? proper proportions of the electrodes for minimum loss:

in which S is-the cross section of the elec trodes in square inches, Ltheir length in inches, C the current in amperes, r, K.- and T being thesame as above. The electrodes must have this proportion in order toobtain This second formula gives the ratio of the section to the lengthof the electrodes and therefore leaves a choice of either,-but not ofboth. The length should be made as short as possible; it is usuallydetermined by the general design and thickness of'the furnace walls orother considerations. The quantity of electrode material increases asthe square of the length. It follows, therefore. that in accordance withmy discoveries and invention, I may greatly reduce the size of, andtherefore cheapen, the electrodes heretofore used in the artand at thesame time secure a minimum loss of energy in the electrodes,

thus leaving greater amounts of energy for useful work within thefurnace and. in consequence, increasing the efficiency of the furnace.And in a furnace involving the pinch effect as herein described, with acertain amount of energy available. there remains, because of thiselectrode efficiency, a greater amount of energy and current availablewithin the furnace, and'the greater current thus available not onlyproduces greater heating effect, but also materially increases the pincheffect, since that effect is dependent upon the square of the current.

If by the electrode efficiency is meant the ratio of the energy set freein the interior of the furnace, that is, between the hot ends of the twoelectrodes, divided by the ,total energy between the two cold ends, thenfor a given minimum loss in the electrodes, this efficiency willevidently be higher the greater the drop of voltage between the hotends, as compared with the drop of voltage in one of the electrodes. Bymy invention the latter may be made very small, much smaller thanheretofore, hence for a given ,current and voltage of a furnace therewill be more useful heat generated in the furnace. But to increase thiseificiency still more the drop of 'voltage between the two hot endsshould be made as great as possible. To do this with a liquid resistermay require this resister to be made long and small in section, hence Imay in 'those cases prefer to use the are as this has a relatively highdrop of potential in a small space. Or still better I may use severalarcs in series.

In Figs. 5, 7, 8 and 9I have disclosed furnaces involving an electricare or arcs, in certain relations, and the electrodes E, E may be suchas those hereinbefore described,

and the columns of molten material with which they are in direct contactmay be the pinch efi'ect columns hereinbefore described.

In Fig. 5 I have shown an arc furnace having the metallic electrodes E,E communicating'with the separated baths B, B of molten material, adividing. wall or member S being provided. The are may be started by abridge piece such as shown in Fig. 6 made of the same metal as that inthe baths B, B, by placing the same ovei the dividing member S; themember then melts and an arc is formed between the two baths B Y and B.Or the arc may be started by granular conducting material extendingoverthe member S into contact with the two baths, or the baths may beagitated to come momentarily into contact with each other above themember S, or any other means may be employed. The dividing member S maybe kept from fusing by a circulation of water or other cooling materialthrough the opening or. tube T. Or the magnetic blow-out principle maybe used to keep the are farther from the dividing member S. Or themember S may be made of a conductor of the second-class which willconduct after being heated by the arc.

' If desired. two or more arcs may be used asshown in Figs. 7 and 8,thereby obtaining a higher heat efficiency and a single large hearthsurface. It will be noted from Figs.

7 and 8 that the openings I in the cover or roof of the furnace aredisposed opposite the columns and the electrodes in communication withthese columns, whereby the columns or channels are readily accessiblethrough the roof or covering of the furnace. Or the arc may beautomatically started by the pinch effect as shown in Fig. 9, and inwhich the metal levelis higher than the top of the dividing member S.The current passing through the constricted portion over the dividingmember S will, when properly proportioned, part the metal and formanarc.

.In all ofthe forms of furnaces herein shown, it will be noticed thatthe two terminals or electrodes may be brought out close together,thereby facilitating the connections to the transformer and thusincreasing the power factor, since the area inclosed by the conductingloop formed Within the furnace is greatly reduced. Also that theelectrodes are not consumed and therefore do not contaminate the fusedproduct and do not have tobe advanced into the furnace. In consequence,the construction of the furnace is greatly simplified and cheapened.Unless proportioned as I have shown, the losses through metal electrodesmay become very large due to their high heat conductivity.

By the construction and mode of operation of the furnaces I have hereindescribed,

I am enabled to heat the molten metal to so high a temperature thatthere is a rapid and great transfer of heat from the mass of cause of.this rapidity of transfer of heat said columns or channels, the squareof the from the molten metal to the slags or other materials, agivenamount of metal may be treated in a smaller furnace.

While I have herein disclosed improvements in the electrodes themselvesof application to electric furnaces generally, I herein claim suchelectrodes only in combination with other features, and reserve for adivi- "sional application the subject matter relating to theseelectrodes themselves, or their employment in other combinations.

Vvhat I claim is:

1. In an electric furnace, a hearth for containing a mass of moltenmaterial, columns or channels communicating with said hearth and adaptedto be filled with molten material in communication with said molten massto constitute the furnace resister, and electrodes in end oncommunication with current transmitted through said electrodes to themolten material in said columns. or

channels with relation to the cross section of said columns or channelsbeing great,

whereby said mass of molten material is- I automatically stirred.

resister, said column being of such cross section compared wlth' thefurnace current transmitted that the pinch effect is produced, whereby,said molten material circuted through each resister to the crosssectionof said resister being great, whereby the molten material isautomatically agitated.

5. .In an electric furnace employing alternating current, a mass ofmolten material through which alternating current is passed, the ratioof the square of said current to the cross section of said mass beinggreat, whereby the molten material is. automatically agitated, and incontact with said molten mass electrodes proportioned for minimumelectrode loss, whereby the distance between said electrodes is smalland the power factoijof the furnace is great.

6. In an electric furnace, the combination with a hearth adapted to holda molten mass, of a channel adapted to contain a column of moltenconducting material in communication with said molten mass, and a sideor branch channel forming a communication between said first namedchannel and said hearth, the ratio of the square of the furnace currenttransmitted through the column in said first mentioned channel to thecross section of said column being great, whereby the molten material isautomatically agitated. I

7. In an electric furnace, the combination with a hearth adapted to holda molten mass,

of a channel adapted. to contain a column of molten conducting materialin communication with saidzmolt'en mass, and a side or branch channelforming a communication between said first named channel and saidhearth, the ratios of the squares of the furnace currents transmittedthrough the columns in said channels to the cross sections of saidcolumns being great, whereby the molten material is automaticallyagitated.

8. In an electric furnace, a column of conducting material serving as aresister, the ratio of the square of the furnace current transmittedthrough said column to the cross section of said column being great,

whereby the molten material is automatiresistance to a temperaturesubstantially equal to furnace temperature.

9. In an-electric furnace, the combination with a hearth adapted to holda molten mass,

an electrode, a pluralityof channels adapted to contain moltenconducting material in communication With said electrode and with saidmolten mass, the ratios of the squares of the furnace currentstransmitted through the conducting material in said channels to thecross sections of said channels being great, whereby the molten materialis automatically agitated.

10. In an electric furnace, a hearth adapt- 1 ed to hold a mass ofmolten material, and a channel communicating with said hearth andadapted to contain a column of molten material in communication withsaid mass of molten material, and a contraction in said channel near itscommunication with said hearth.

11. An electric furnace provided witha hearth for containing a bath ofmolten conducting material, a molten column incommunication with saidbath, the ratio of the square of the furnace current transmitted throughsaid column to the cross section of said column being great, whereby themolten material is automatically agitated by theresulting pinch effect.

12. In an electric furnace, the combination with a mass of moltenmaterial, of a molten mass in communication therewith serving asresister, the ratio of the square of the current through said resisterto its cross section being great, whereby circulation of molten metal isproduced, and an electrode in communication with said resisterhavingsuch dimensions that the C R 40 heat developed in said electrode by thecurrent traversing said resister shall be equal to substantially twicethe heat conduction loss through said electrode when no current i isflowing.

-13. In an electric furnace, a mass of molten conducting material, meansfor passing an electric current through said molten material, and meansfor giving to said molten material through which said current is passeda predetermined cross section, the ratio of the square of said currenttrans mitted through said material to said cross section of saidmaterial being great, whereby the molten material is automaticallyagitated by the resulting pinch effect.

'14. In an electric furnace, a mass of molten conducting material, meansfor passing an electric current through said molten ma terial, and meansfor giving to said molten material through. which? said current ispasseda predetermined cross section, the

ratio of the square of said current Lransnlitted through said moltenmaterial to said cross section of said molten materlal being great,whereby the pinch effect caused in said material and the hydro-staticpressure due to said material causes circulation, or agitation of saidmolten material.

1 In an electric furnace, a molten conducting mass, means for passinganelectric current therethrough, and means for giving to said mass throughwhich said current is passed a predetermined cross section, the ratio ofthe square of the current transmitted through said mass to said crosssec- 76 tion of said mass being great, whereby the pinch effect isproduced in said mass to cause a continued circulation of said moltenmass. v

16. The method of treating a mass of 80 molten material in an electricfurnace, which consists in passing through said molten material anelectric current so proportioned to the cross section of said materialas to pro duce the pinch effect, whereby said molten,

material is automatically agitated.

. 17. The method of treating a mass of molten material in an electricfurnace, which consists in passing through said molten ma terial anelectric current so proportioned to the cross section of said materialas to produce the pinch effect, whereby said molten material isautomatically continuously stirred.

18. The method of treating a bath of molten material in an electricfurnace, which consists in passing an electric current through a mass ofmolten material in communication with said bath, said electric currentso proportioned with respectto the cross section of said mass as toproduce the pinch effect, whereby the molten material is automaticallyagitated.

19. The method of treatinga bath of molten material in an electricfurnace, which consists in passing an electric current through a mass ofmolten material in communicatiomwith said bath. said electric current soproportioned with respect to the cross section of said mass as toproduce the pinch effect, whereby the molten material is automaticallycontinuously stirred.

Q0. The method of treating a mass of molten material, which consists inpassing through said molten material an electric current so proportionedwith respect to the cross section of said-material as to produce thepinch effect, said pinch effect and the hydrostatic pressure due to saidmolten material causing a continued circulation of said molten material.

21. The method of treating a mass of 11101- ten material, which consistsin passing through a portion of the entire mass an electric current soproportioned with respect to the cross section of said portion that thepinch effect is produced, whereby continued uu tomatic circulation ofthe molten material is produced.

99. The furnace process of treating a mass 13.

of .molten material, and drawing an are be- I of molten material, whichconsists in passing through a portion of the mass ofmolten material anelectric current, the current strength compared with-the cross sectionof said portion of the molten material being so great that the pincheffect is produced, whereby automatic circulation of the molten materialis produced. p

23. In an electric furnace, a mass of molten material, means for passingan electric current through said molten material, and means for givingto. said molten material through which said current is passed apredetermined cross section, said current passing through said crosssection of said material electrically heating said mass of moltenmaterial,.and the strength of'said heating current compared with saidcross section of said molten material being great, whereby said moltenmaterial is automatically agitated by the resulting pinch effect.

24. The method of consists in passing through said molten material anelectric current sufficient to produce a recurring or continued pincheffect.

25. The method of treating a mass of molten material in an electricfurnace, which consists in passing through a. portion of said mass ofmolten material an electric current sufficient to produce in saidportion a recurring or continued pinch effect, whereby said moltenmaterial is automatically agitated. 26. The method of treating a mass ofmolten material in an electric furnace, which consists in passingthrough said molten material a heating current, said heating currentcausing in said material a recurring or continued pinch effect, wherebysaid heating current automatically stirs said molten material.

27 The method of treating a mass of molten material in an electricfurnace, which consists in passing a heating current through a register,said heating current being sufficient to cause a recurring or continuedpinch effect, whereby said heating current automatically stirs saidmolten material.

28. As an improvement in the art of operating an electric furnace, theprocess which consists in passing through a .mass of molten material acurrent sufficient to produce a pinch effect to'divide the mass tweenthe parts of said mass so divided.

29. The process of treating a mass of molten material in an electricfurnace, which consists in passing through said material a current tocause a recurring or continued pinch efi'ect, and subjecting said moltenmaterial to the effects of an electric are.

treating a mass of molten material in an electric furnace, which 30. Theprocess of treating a mass of molten material in an electric furnace,which consists in passing through said molten material a current causinga recurring or continued pinch effect, producing an electric arc, andsubjecting said molten material to heat derived from said arc.

31. The electric furnace process which consists in bringing raw materialinto contact with a bath of molten material, passing an electric currentthrough said molten material to produce the pinch efiect., whereby saidmolten material is automatically stirred, liberating combustible gasesfrom said raw material, and burning said gases in contact with said rawmaterial within said furnace to preheat said raw material.

32. The electric furnace process which consists in bringing raw materialinto contact with a bath of molten material, and passing an electriccurrent through said molten material to produce a pinch efiect, wherebysaid molten material is projected against said raw material to transferheat thereto.

33. The process of reducing oXid ores, which consists in producing abath of molten metal reduced from the oxid ore, passing a currentthrough said molten metal to pro duce therein the pinch efiect, wherebysaid molten metal is brought into intimate contact with the oxid ore,and dissolving car-- bon and the oxid ore in said molten metal, wherebythe dissolved carbon and dissolved oXid ore react upon each other toreduce said oXid ore to metal. I

34:- The process of reducing oXid ores, which consists in producingmolten metal, bringing the oxid ore and carbon intocontact with saidmolten metal, passing an electric current through said molten metal toproduce the pinch efiect, whereby said molten metal is brought intointimate contact with said carbon and oXid ore, dissolving carbon andthe oxid ore in said molten metal, liberating combustible gases, andburning said combustible gases and adding resulting heat to the rawmaterial.

The process of reducing oxid ores.

opening in said cover in substantial alinement' with said channel.

37 Theaele ctric furnace process which consists in passing a currentthrough molten i; of said current through said molten materialCorrections in Letters Patent No. 988,936.

material, said current producing heat in said In testimony whereof Ihave hereunto molten material sufficient to maintain the affixed mysignature in the presence of the 10 same molten, and the ratio of thesquare of two subscribing witnesses.

said current to the cross section of the path CARL HERING.

Witnesses:

MAY E. GILL, A. E. STEINBOOK.

being great, whereby said molten materlal is automatically stirred bythe resultlng pinch effect. I

It is hereby certified that in Letters'Patent No. 988,936, granted April4, 1911, upon the application of Carl Hering, of Philadelphia,Pennsylvania, for an improvement in Electric-Furnace Processes andElectric Furnaces, errors appear in the printed specification requiringcorrection as follows: Throughout the specification and claims the wordresister should read resistor and the word resisters should readresistors; page 2, line 12, after the word material the. word 01- shouldbe inserted; page 7, line 37, the word metal should read material; page8, line v 18, the word register should read resistor; and that the saidLetters Patent should be read with these corrections therein that thesame may conform to the record of the case in the Patent Oflice.

Signed and sealed this 9th day of May, A. 13., 1911..

[SEAL] o. o. BILLINGS,

Acting Oomwrssz'oner 0 f Patents.

